In the aircraft industry, aircraft are commonly built by assembling barrel sections together to form a fuselage. The barrel sections are coupled together at the end portions of the barrels (e.g., spliced sections of the barrels) in which each barrel section may include a bulkhead structure with one or more layers of stacked outer sheets attached to the outer section of the bulkhead. Where adjacent spliced sections of the barrel sections interface, there can be significantly more layers of stacked outer sheets in which to fasten to the bulkhead outer section(s).
Typically, near the spliced section of a barrel section, there is a pilot hole in the bulkhead that may be, for example, machined in the interior surface of the bulkhead outer section. The pilot hole is used as a location guide for drilling through the bulkhead outer section and into layers of stacked outer sheets to form an opening therethrough for fastening. A series of bushings with stepwise increases in inner diameter (ID) may be used with corresponding drill bits with stepwise increases in outer diameter (OD) to assist in drilling through the pilot hole including the bulkhead outer section and the layers of stacked outer sheets to form a desired sized OD opening for fastening.
Bulkhead structures are typically machined and unfortunately there can be considerable part to part variation including variation in the location of the pilot holes. Additionally, there is often limited working space between the interior webs of the bulkhead and the bulkhead outer structure for drilling through the pilot hole. As such, it can be challenging to consistently align each of the bushings in a series of bushings with stepwise increases in ID as an aid for drilling, and to consistently drill “true” and “round” through the pilot hole, the bulkhead outer section, and the adjacent layers of stacked outer sheets to form a desired sized OD opening therethrough for fastening.
Accordingly, it is desirable to provide an improved drilling aid and a method for drilling using such a drilling aid that overcome some or all of the foregoing issues. Furthermore, other desirable features and characteristics of the various embodiments described herein will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.